Haemophilus Influenzae type B (HiB) is a serious bacteria infection which more commonly affect children below five years old as compared to adults. It can spread from person to person. A carrier of HiB may have the bacteria in their nose and mouth but may not have any symptoms but they can pass the bacteria to others. If the bacteria infection spread to the lungs or into the bloodstream to form invasive disease, it can cause serious complications. Haemophilus influenzae prior to the introduction of vaccination is a cause for childhood meningitis and pneumonia. In severe case it can be disseminated and cause severe sepsis. Severe infection can cause mortality.

The expression of the polysaccharide capsule increases the bacterial virulence and this is associated with severe form of the disease. The vaccine confers protection through the introduction of anticapsular antibodies and induce immunological memory. The vaccination also reduces the carriage of the bacteria in the nose/mouth of carriers hence reducing the risk of transmission to others and thus increase herd immunity in the process.

Vaccine regime

HiB vaccine is usually given in combination with other vaccines in the form of the commonly used five-in-one vaccine and six-in-one vaccines.

The first dose is given at 2 months of age, second dose at 4 months of age and the third dose at 6 months of age. A booster at 12-15 months of age. Children above 5 years old and adults do not need HiB vaccination unless they do not have spleen (asplenia), have sickle cell disease, undergoing splenectomy or after bone marrow transplant. There is also another combination vaccine with meningitis C i.e. (HiB/Meningitis C). The vaccine is injected intra-muscularly into the anterior lateral aspect of the thigh or upper arm. It can be given together with other vaccines like hepatitis B, MMR and meningitis C. But it should be shot at different sites (different limb). Contraindications to vaccination

1. Patients with allergy to neomycin, streptomycin and polymyxin B as they may be present in small amounts in the vaccine.

2. Patients who has anaphylactic reaction to the vaccine. 3. Infants younger than 6 weeks of age. 4. Patients who are moderately ill with fever and with systemic symptoms should not take the vaccine until they recover.

Reactions to vaccineMajor complications from Hib vaccination like allergic anaphylactic reaction is very rare like one in a million chance. Patients with anaphylactic reaction will have onset of angioedema (swelling of face and throat), difficulty in breathing, hives, weakness, dizziness and palpitations within minutes to hours post vaccination.

But minor reaction may occur at site of injection like redness, swelling and warmth. Some may have fever. These usually occur 2-3 days post vaccination and are not common. It will resolve with time.